SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    822, 662, 806, 805, 804, 803, 802, 801, 
    800, 799, 796, 792, 786, 782, 744, 743, 
    742, 741, 727, 720, 718, 716, 713, 701, 
    671, 670, 664, 663, 658, 657, 656, 377, 
    371, 369, 368, 362, 228, 195, 192, 189, 
    71, 10, 9
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00075

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "30.11"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 43,
      "rows_produced_per_join": 43,
      "filtered": "100.00",
      "index_condition": "((`betaatif_store`.`cscart_product_descriptions`.`product_id` in (822,662,806,805,804,803,802,801,800,799,796,792,786,782,744,743,742,741,727,720,718,716,713,701,671,670,664,663,658,657,656,377,371,369,368,362,228,195,192,189,71,10,9)) and (`betaatif_store`.`cscart_product_descriptions`.`lang_code` = 'en'))",
      "cost_info": {
        "read_cost": "25.81",
        "eval_cost": "4.30",
        "prefix_cost": "30.11",
        "data_read_per_join": "163K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ]
    }
  }
}